2.47 [EX02-047] The Office of Coal, Nuclear, Electric and Alternate Fuels reported the following data as the costs (in cents) of the average revenue per kilowatt-hour for sectors in Arkansas:

6.61 7.61 6.99 7.48 5.10 7.56 6.65 5.93 7.92 5.52 7.47 6.79 8.27 7.50 7.44 6.36 5.20 5.48 7.69 8.74 5.75 6.94 7.70 6.67 4.59 5.96 7.26 5.38 8.88 7.49 6.89 7.25 6.89 6.41 5.86 8.04

a. Prepare a grouped frequency distribution for the average revenue per kilowatt-hour using class boundaries 4, 5, 6, 7, 8, 9.

b. Find the class width.

c. List the class midpoints.

d. Construct a relative frequency histogram of these data.